<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title></title>
</head>
<body>
<script>
	//var a=[1,2,3,4,5,6,7,8,9];
	//document.write(a.length)长度
	//decument.write(typeof(a));
	//decument.write("你好");
	//console.log(typeof(a));
	
	
	
	
	//var a=[1,2,3,4,5,6,7,8,9];
	//for(var index in a){
		//document.write(index+"</br>")	输出in a
	//}
	
	
	/*for(var x of a[0]){
		//document.write(a[0][0])//输入0  再加一个【】输入=1
		document.write(x+"");
	}
	for(var x of a[1]){
		
		document.write(x+"");
	}
	for(var x of a[2]){
		
		document.write(x+"");
	}*/
	var a=[[1,2,3],[4,5,6],[7,8,9]];
		for(var i in a){
		for(var x of a[i]){
			document.write(x+" ");
		}
		    document.write("</br>");
	}
	
</script>
</body>
</html>
